Comparison of passive cavitation imaging and plane wave B-mode imaging for monitoring histotripsy ablation

Abstract

Histotripsy utilizes the oscillations of bubbles within a cloud for transcutaneous mechanical ablation of tissue and is currently under development to treat benign prostatic hyperplasia. The bubble clouds are hyperechoic, enabling standard B-mode imaging to be used for image guidance. The volumetric oscillations of the bubbles also generate acoustic emissions that can be imaged. The purpose of this study was to demonstrate the feasibility of monitoring histotripsy-induced ablation with passive cavitation images. Prostate tissue phantoms were exposed to mechanically ablative, 1-MHz histotripsy pulses over a range of pulse durations (5—20 ms) and peak negative pressures (12—23 MPa). Bubble clouds generated by the histotripsy pulses were monitored with a linear array using passive cavitation imaging (PCI) and plane wave B-mode imaging. The utility of PCI and B-mode imaging to predict the phantom ablation zone was assessed using receiver operating characteristic (ROC) curve analysis. The area under the ROC cu...